Davidlohr Bueso | d65817b | 2015-05-08 11:37:59 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2015 Davidlohr Bueso. |
| 3 | * |
| 4 | * Block a bunch of threads and let parallel waker threads wakeup an |
| 5 | * equal amount of them. The program output reflects the avg latency |
| 6 | * for each individual thread to service its share of work. Ultimately |
| 7 | * it can be used to measure futex_wake() changes. |
| 8 | */ |
| 9 | |
Arnaldo Carvalho de Melo | 8a15858 | 2016-07-06 12:14:56 -0300 | [diff] [blame] | 10 | /* For the CLR_() macros */ |
| 11 | #include <pthread.h> |
| 12 | |
Arnaldo Carvalho de Melo | 9c304f6 | 2016-07-07 11:01:46 -0300 | [diff] [blame] | 13 | #include <signal.h> |
Davidlohr Bueso | d65817b | 2015-05-08 11:37:59 -0700 | [diff] [blame] | 14 | #include "../util/stat.h" |
Josh Poimboeuf | 4b6ab94 | 2015-12-15 09:39:39 -0600 | [diff] [blame] | 15 | #include <subcmd/parse-options.h> |
Arnaldo Carvalho de Melo | 86695f5 | 2016-07-11 10:05:52 -0300 | [diff] [blame^] | 16 | #include <linux/compiler.h> |
Arnaldo Carvalho de Melo | 9c304f6 | 2016-07-07 11:01:46 -0300 | [diff] [blame] | 17 | #include <linux/kernel.h> |
| 18 | #include <errno.h> |
Davidlohr Bueso | d65817b | 2015-05-08 11:37:59 -0700 | [diff] [blame] | 19 | #include "bench.h" |
| 20 | #include "futex.h" |
| 21 | |
| 22 | #include <err.h> |
| 23 | #include <stdlib.h> |
| 24 | #include <sys/time.h> |
Davidlohr Bueso | d65817b | 2015-05-08 11:37:59 -0700 | [diff] [blame] | 25 | |
| 26 | struct thread_data { |
| 27 | pthread_t worker; |
| 28 | unsigned int nwoken; |
| 29 | struct timeval runtime; |
| 30 | }; |
| 31 | |
| 32 | static unsigned int nwakes = 1; |
| 33 | |
| 34 | /* all threads will block on the same futex -- hash bucket chaos ;) */ |
| 35 | static u_int32_t futex = 0; |
| 36 | |
| 37 | static pthread_t *blocked_worker; |
| 38 | static bool done = false, silent = false, fshared = false; |
| 39 | static unsigned int nblocked_threads = 0, nwaking_threads = 0; |
| 40 | static pthread_mutex_t thread_lock; |
| 41 | static pthread_cond_t thread_parent, thread_worker; |
| 42 | static struct stats waketime_stats, wakeup_stats; |
| 43 | static unsigned int ncpus, threads_starting; |
| 44 | static int futex_flag = 0; |
| 45 | |
| 46 | static const struct option options[] = { |
| 47 | OPT_UINTEGER('t', "threads", &nblocked_threads, "Specify amount of threads"), |
| 48 | OPT_UINTEGER('w', "nwakers", &nwaking_threads, "Specify amount of waking threads"), |
| 49 | OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"), |
| 50 | OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"), |
| 51 | OPT_END() |
| 52 | }; |
| 53 | |
| 54 | static const char * const bench_futex_wake_parallel_usage[] = { |
| 55 | "perf bench futex wake-parallel <options>", |
| 56 | NULL |
| 57 | }; |
| 58 | |
| 59 | static void *waking_workerfn(void *arg) |
| 60 | { |
| 61 | struct thread_data *waker = (struct thread_data *) arg; |
| 62 | struct timeval start, end; |
| 63 | |
| 64 | gettimeofday(&start, NULL); |
| 65 | |
| 66 | waker->nwoken = futex_wake(&futex, nwakes, futex_flag); |
| 67 | if (waker->nwoken != nwakes) |
| 68 | warnx("couldn't wakeup all tasks (%d/%d)", |
| 69 | waker->nwoken, nwakes); |
| 70 | |
| 71 | gettimeofday(&end, NULL); |
| 72 | timersub(&end, &start, &waker->runtime); |
| 73 | |
| 74 | pthread_exit(NULL); |
| 75 | return NULL; |
| 76 | } |
| 77 | |
| 78 | static void wakeup_threads(struct thread_data *td, pthread_attr_t thread_attr) |
| 79 | { |
| 80 | unsigned int i; |
| 81 | |
| 82 | pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_JOINABLE); |
| 83 | |
| 84 | /* create and block all threads */ |
| 85 | for (i = 0; i < nwaking_threads; i++) { |
| 86 | /* |
| 87 | * Thread creation order will impact per-thread latency |
| 88 | * as it will affect the order to acquire the hb spinlock. |
| 89 | * For now let the scheduler decide. |
| 90 | */ |
| 91 | if (pthread_create(&td[i].worker, &thread_attr, |
| 92 | waking_workerfn, (void *)&td[i])) |
| 93 | err(EXIT_FAILURE, "pthread_create"); |
| 94 | } |
| 95 | |
| 96 | for (i = 0; i < nwaking_threads; i++) |
| 97 | if (pthread_join(td[i].worker, NULL)) |
| 98 | err(EXIT_FAILURE, "pthread_join"); |
| 99 | } |
| 100 | |
| 101 | static void *blocked_workerfn(void *arg __maybe_unused) |
| 102 | { |
| 103 | pthread_mutex_lock(&thread_lock); |
| 104 | threads_starting--; |
| 105 | if (!threads_starting) |
| 106 | pthread_cond_signal(&thread_parent); |
| 107 | pthread_cond_wait(&thread_worker, &thread_lock); |
| 108 | pthread_mutex_unlock(&thread_lock); |
| 109 | |
| 110 | while (1) { /* handle spurious wakeups */ |
| 111 | if (futex_wait(&futex, 0, NULL, futex_flag) != EINTR) |
| 112 | break; |
| 113 | } |
| 114 | |
| 115 | pthread_exit(NULL); |
| 116 | return NULL; |
| 117 | } |
| 118 | |
| 119 | static void block_threads(pthread_t *w, pthread_attr_t thread_attr) |
| 120 | { |
| 121 | cpu_set_t cpu; |
| 122 | unsigned int i; |
| 123 | |
| 124 | threads_starting = nblocked_threads; |
| 125 | |
| 126 | /* create and block all threads */ |
| 127 | for (i = 0; i < nblocked_threads; i++) { |
| 128 | CPU_ZERO(&cpu); |
| 129 | CPU_SET(i % ncpus, &cpu); |
| 130 | |
| 131 | if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu)) |
| 132 | err(EXIT_FAILURE, "pthread_attr_setaffinity_np"); |
| 133 | |
| 134 | if (pthread_create(&w[i], &thread_attr, blocked_workerfn, NULL)) |
| 135 | err(EXIT_FAILURE, "pthread_create"); |
| 136 | } |
| 137 | } |
| 138 | |
| 139 | static void print_run(struct thread_data *waking_worker, unsigned int run_num) |
| 140 | { |
| 141 | unsigned int i, wakeup_avg; |
| 142 | double waketime_avg, waketime_stddev; |
| 143 | struct stats __waketime_stats, __wakeup_stats; |
| 144 | |
| 145 | init_stats(&__wakeup_stats); |
| 146 | init_stats(&__waketime_stats); |
| 147 | |
| 148 | for (i = 0; i < nwaking_threads; i++) { |
| 149 | update_stats(&__waketime_stats, waking_worker[i].runtime.tv_usec); |
| 150 | update_stats(&__wakeup_stats, waking_worker[i].nwoken); |
| 151 | } |
| 152 | |
| 153 | waketime_avg = avg_stats(&__waketime_stats); |
| 154 | waketime_stddev = stddev_stats(&__waketime_stats); |
| 155 | wakeup_avg = avg_stats(&__wakeup_stats); |
| 156 | |
| 157 | printf("[Run %d]: Avg per-thread latency (waking %d/%d threads) " |
| 158 | "in %.4f ms (+-%.2f%%)\n", run_num + 1, wakeup_avg, |
| 159 | nblocked_threads, waketime_avg/1e3, |
| 160 | rel_stddev_stats(waketime_stddev, waketime_avg)); |
| 161 | } |
| 162 | |
| 163 | static void print_summary(void) |
| 164 | { |
| 165 | unsigned int wakeup_avg; |
| 166 | double waketime_avg, waketime_stddev; |
| 167 | |
| 168 | waketime_avg = avg_stats(&waketime_stats); |
| 169 | waketime_stddev = stddev_stats(&waketime_stats); |
| 170 | wakeup_avg = avg_stats(&wakeup_stats); |
| 171 | |
| 172 | printf("Avg per-thread latency (waking %d/%d threads) in %.4f ms (+-%.2f%%)\n", |
| 173 | wakeup_avg, |
| 174 | nblocked_threads, |
| 175 | waketime_avg/1e3, |
| 176 | rel_stddev_stats(waketime_stddev, waketime_avg)); |
| 177 | } |
| 178 | |
| 179 | |
| 180 | static void do_run_stats(struct thread_data *waking_worker) |
| 181 | { |
| 182 | unsigned int i; |
| 183 | |
| 184 | for (i = 0; i < nwaking_threads; i++) { |
| 185 | update_stats(&waketime_stats, waking_worker[i].runtime.tv_usec); |
| 186 | update_stats(&wakeup_stats, waking_worker[i].nwoken); |
| 187 | } |
| 188 | |
| 189 | } |
| 190 | |
| 191 | static void toggle_done(int sig __maybe_unused, |
| 192 | siginfo_t *info __maybe_unused, |
| 193 | void *uc __maybe_unused) |
| 194 | { |
| 195 | done = true; |
| 196 | } |
| 197 | |
| 198 | int bench_futex_wake_parallel(int argc, const char **argv, |
| 199 | const char *prefix __maybe_unused) |
| 200 | { |
| 201 | int ret = 0; |
| 202 | unsigned int i, j; |
| 203 | struct sigaction act; |
| 204 | pthread_attr_t thread_attr; |
| 205 | struct thread_data *waking_worker; |
| 206 | |
| 207 | argc = parse_options(argc, argv, options, |
| 208 | bench_futex_wake_parallel_usage, 0); |
| 209 | if (argc) { |
| 210 | usage_with_options(bench_futex_wake_parallel_usage, options); |
| 211 | exit(EXIT_FAILURE); |
| 212 | } |
| 213 | |
| 214 | sigfillset(&act.sa_mask); |
| 215 | act.sa_sigaction = toggle_done; |
| 216 | sigaction(SIGINT, &act, NULL); |
| 217 | |
| 218 | ncpus = sysconf(_SC_NPROCESSORS_ONLN); |
| 219 | if (!nblocked_threads) |
| 220 | nblocked_threads = ncpus; |
| 221 | |
| 222 | /* some sanity checks */ |
| 223 | if (nwaking_threads > nblocked_threads || !nwaking_threads) |
| 224 | nwaking_threads = nblocked_threads; |
| 225 | |
| 226 | if (nblocked_threads % nwaking_threads) |
| 227 | errx(EXIT_FAILURE, "Must be perfectly divisible"); |
| 228 | /* |
| 229 | * Each thread will wakeup nwakes tasks in |
| 230 | * a single futex_wait call. |
| 231 | */ |
| 232 | nwakes = nblocked_threads/nwaking_threads; |
| 233 | |
| 234 | blocked_worker = calloc(nblocked_threads, sizeof(*blocked_worker)); |
| 235 | if (!blocked_worker) |
| 236 | err(EXIT_FAILURE, "calloc"); |
| 237 | |
| 238 | if (!fshared) |
| 239 | futex_flag = FUTEX_PRIVATE_FLAG; |
| 240 | |
| 241 | printf("Run summary [PID %d]: blocking on %d threads (at [%s] " |
| 242 | "futex %p), %d threads waking up %d at a time.\n\n", |
| 243 | getpid(), nblocked_threads, fshared ? "shared":"private", |
| 244 | &futex, nwaking_threads, nwakes); |
| 245 | |
| 246 | init_stats(&wakeup_stats); |
| 247 | init_stats(&waketime_stats); |
| 248 | |
| 249 | pthread_attr_init(&thread_attr); |
| 250 | pthread_mutex_init(&thread_lock, NULL); |
| 251 | pthread_cond_init(&thread_parent, NULL); |
| 252 | pthread_cond_init(&thread_worker, NULL); |
| 253 | |
| 254 | for (j = 0; j < bench_repeat && !done; j++) { |
| 255 | waking_worker = calloc(nwaking_threads, sizeof(*waking_worker)); |
| 256 | if (!waking_worker) |
| 257 | err(EXIT_FAILURE, "calloc"); |
| 258 | |
| 259 | /* create, launch & block all threads */ |
| 260 | block_threads(blocked_worker, thread_attr); |
| 261 | |
| 262 | /* make sure all threads are already blocked */ |
| 263 | pthread_mutex_lock(&thread_lock); |
| 264 | while (threads_starting) |
| 265 | pthread_cond_wait(&thread_parent, &thread_lock); |
| 266 | pthread_cond_broadcast(&thread_worker); |
| 267 | pthread_mutex_unlock(&thread_lock); |
| 268 | |
| 269 | usleep(100000); |
| 270 | |
| 271 | /* Ok, all threads are patiently blocked, start waking folks up */ |
| 272 | wakeup_threads(waking_worker, thread_attr); |
| 273 | |
| 274 | for (i = 0; i < nblocked_threads; i++) { |
| 275 | ret = pthread_join(blocked_worker[i], NULL); |
| 276 | if (ret) |
| 277 | err(EXIT_FAILURE, "pthread_join"); |
| 278 | } |
| 279 | |
| 280 | do_run_stats(waking_worker); |
| 281 | if (!silent) |
| 282 | print_run(waking_worker, j); |
| 283 | |
| 284 | free(waking_worker); |
| 285 | } |
| 286 | |
| 287 | /* cleanup & report results */ |
| 288 | pthread_cond_destroy(&thread_parent); |
| 289 | pthread_cond_destroy(&thread_worker); |
| 290 | pthread_mutex_destroy(&thread_lock); |
| 291 | pthread_attr_destroy(&thread_attr); |
| 292 | |
| 293 | print_summary(); |
| 294 | |
| 295 | free(blocked_worker); |
| 296 | return ret; |
| 297 | } |